Sustainability is the word this whole course is built around, and it is used so loosely outside the classroom that it has almost stopped meaning anything. In ESS it has a precise definition, three pillars, and two competing ways of drawing the relationship between them.
📘 What you need to know
Sustainability is the ability of a system to endure and remain viable over time.
In socio-ecological systems it means resources are not depleted and conditions for future generations are not compromised.
Enhancing a system’s resilience increases its sustainability.
The three pillars are environmental, social and economic sustainability. They are interdependent and must be balanced.
Weak sustainability models show the three pillars merely overlapping.
Strong sustainability models show the economy nested within society, and both nested within the environment.
There can be no long-term economic sustainability without environmental sustainability.
Defining sustainability
Sustainability refers to the ability of a system to endure and remain viable — to maintain its functionality and integrity — over time.
DefinitionSustainability — the ability of a system to endure and remain viable over time. In socio-ecological systems, it means using resources responsibly so they are not depleted and conditions for future generations are not compromised.
All human activities are interconnected within systems, and enhancing the resilience of those systems increases their sustainability. That is achieved by making sure the system’s components are properly maintained. A sustainable agricultural system, for instance, has to account for soil health, water management and biodiversity together in order to stay productive long term without degrading the environment.
This links straight back to 1.2. Resilience was a system’s ability to absorb disturbance and avoid tipping points. Sustainability is what you get when a system keeps that ability indefinitely. If you can explain resilience, you are most of the way to explaining sustainability.
The three pillars
Sustainability has three pillars: environmental, social and economic. They are interdependent and must be balanced for overall sustainability. A business adopting green practices (environmental) might also improve employee wellbeing (social) and cut unnecessary spending (economic), improving its long-term sustainability on all three fronts at once.
In the weak model you could shrink the environment circle and still have an economy. In the strong model, shrinking it shrinks everything inside it.
Weak sustainability models only show an overlap between the three pillars. This does not account for the importance of the intricate relationships between them.
Strong sustainability models show the economy nested within society, and both nested within the natural environment, emphasising the interconnectivity of the three pillars.
Environmental sustainability
This focuses on the responsible use and management of natural resources so they are replenished and preserved, and on allowing whole ecosystems to recover and regenerate.
Strategy
What it involves
Example
Resource management
Practices that allow resources used to be replaced, such as sustainable forestry
Sustainable aquaculture and fishery management, where quotas and habitat restoration replenish fish stocks
Pollution control
Minimising pollution and its harm to ecosystems and human health
Waste management schemes such as recycling programmes and waste-to-energy plants
Biodiversity conservation
Preserving biodiversity to keep ecosystems resilient and able to adapt
Reintroduction of native species and habitat restoration initiatives
Active regeneration
Going beyond conservation to restore degraded ecosystems to a more natural state
Wetland restoration in the Norfolk Broads, re-establishing native vegetation and hydrology for flood control and water purification
Ecosystem services
Recognising and maintaining services such as clean water, air purification and carbon sequestration
London’s parks and gardens, absorbing pollutants, easing the urban heat island and supporting biodiversity
Long-term perspectives
Planning for the continued health and resilience of ecosystems decades ahead
The UK’s Northern Forest initiative, planting millions of trees to sequester carbon and boost biodiversity
Social sustainability
This focuses on creating inclusive structures and systems that support human wellbeing and the longevity of societies and cultures.
Strategy
What it involves
Example
Community development
Equitable access to resources, services and opportunities for all members
Community gardens, which provide fresh produce, build social connections and improve local food security
Cultural preservation
Maintaining traditions, languages and practices that give societies identity and cohesion
Initiatives reviving Indigenous languages, or protecting cultural heritage sites
Health and education
Access to healthcare, education and other essential services
Public health campaigns on quitting smoking or healthy eating
Economic sustainability
This means creating economic systems that meet present needs without compromising the ability of future generations to meet their own.
Strategy
What it involves
Example
Resource efficiency
Prioritising efficient use of resources, reducing waste and environmental impact
Circular economy principles in manufacturing, designing products for reuse or recycling
Long-term planning
Considering resource availability, technological change and market stability over decades
Investment in renewable energy infrastructure, cutting emissions while creating clean energy jobs
Equitable growth
Reducing inequalities and ensuring fair distribution of resources and opportunities
Microfinance giving marginalised communities access to capital for enterprise
Notice that “long-term planning” appears under both the environmental and economic pillars. That overlap is the point of the model.
Here is the line examiners reward. Because we rely so heavily on natural resources to meet human needs and support economic activity, there can be no long-term economic sustainability without environmental sustainability. To keep economies functioning over time, we must protect the environment first. That single sentence is the strong sustainability model in words.
Worked examples
WE 1
Defining sustainability
Outline what is meant by sustainability and name the three pillars. (3 marks)
Step 1: the definition
Sustainability is the ability of a system to endure and remain viable over time, maintaining its functionality and integrity.
Step 2: what that means in practice
In socio-ecological systems it means using resources responsibly so they are not depleted and conditions for future generations are not compromised.
Step 3: the three pillars
Environmental, social and economic sustainability — interdependent, and all three must be balanced.
Endure over time, without depleting resources or costing the future“future generations” is a marking phrase — include it
WE 2
Weak and strong models
Compare and contrast weak and strong models of sustainability. (4 marks)
Similarity
Both models represent the same three pillars: environmental, social and economic sustainability.
Difference 1: how they are arranged
The weak model shows the three pillars simply overlapping. The strong model shows the economy nested within society, and both nested within the environment.
Difference 2: what each implies
The weak model does not account for the intricate relationships between the pillars. The strong model emphasises their interconnectivity.
The consequence
Only the strong model shows that economic activity is ultimately limited by the environment, which is why there can be no long-term economic sustainability without environmental sustainability.
Same three pillars, but only one model shows which contains whichdraw both if the question allows — the diagram makes the contrast instantly
WE 3
Applying the pillars
Explain how a single project can contribute to all three pillars of sustainability. (3 marks)
The example
Take a community garden established on unused urban land.
Environmental contribution
It provides green space that supports biodiversity and delivers ecosystem services such as absorbing pollutants and reducing the urban heat island effect.
Social contribution
It promotes community development by giving equitable access to fresh produce and building social connections and local resilience.
Economic contribution
It improves local food security, reducing household spending on food and cutting transport costs.
The pillars are interdependent, so one well-designed project can serve all threeany example works if you can name a benefit under each pillar
💡 Exam tips
Use the exact definition: a system’s ability to endure and remain viable over time.
Always mention future generations when defining sustainability.
Be able to draw and label both the weak and strong models.
Say the pillars are interdependent, not merely three separate goals.
Have one named example per pillar ready: Northern Forest, community gardens, microfinance.
Remember the key link: no economic sustainability without environmental sustainability.
⚠ Common mistakes
Treating sustainability as meaning “environmentally friendly”. It has social and economic pillars too.
Presenting the three pillars as independent. They are interdependent.
Confusing weak and strong models. Overlapping is weak; nested is strong.
Saying the strong model ranks the pillars. It shows containment, not importance ranking.
Giving strategies with no examples. Named examples carry the marks.
Forgetting resilience. Increasing a system’s resilience increases its sustainability.
Up next: Sustainable Development and the SDGs. Sustainability describes a state. Sustainable development describes the process of getting there — and the world has agreed a set of targets for it.
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